Tell the video driver that we only want a double buffer.
Defined in SDL_hints.h
By default, most lowlevel 2D APIs will use a triple buffer scheme that wastes no CPU time on waiting for vsync after issuing a flip, but introduces a frame of latency. On the other hand, using a double buffer scheme instead is recommended for cases where low latency is an important factor because we save a whole frame of latency. We do so by waiting for vsync immediately after issuing a flip, usually just after eglSwapBuffers call in the backend's *_SwapWindow function.
Since it's driver-specific, it's only supported where possible and implemented. Currently supported the following drivers: